.page {
    background-color: #eee;
    width: 100vw;
    height: 100vh;
}

.box {
    width: 400px;
    padding: 40px 0;
    background-color: #fff;
    border-radius: 20px;
    position :fixed;
    top: 50%;
    left: 50%;
    margin-left: -200px;
    margin-top: -150px;
    display: flex;
    justify-content: center;
}